Describe the constituents of the carbursiting flame used in oxy-acetylene welding. - Leaving Cert Engineering - Question (k) - 2013

The carbursiting flame contains an excess of acetylene with a lower oxygen supply. This flame produces a specific gas mixture that is critical for certain welding applications.

1. Composition: The carbursiting flame is characterized by a high ratio of acetylene (C2H2) to oxygen (O2), typically with an oxygen content of about 0.85 to 0.95. This excess of acetylene contributes to the flame's unique properties.

2. Flame Structure: The flame consists of the following components:

   • Bright Inner Cone: This is the inner part of the flame where the combustion of acetylene and oxygen occurs. It is indicative of the flame's temperature and energy, which is essential for ensuring adequate heating during the welding process.
   • Acetylene Feather: Surrounding the inner cone, the acetylene feather indicates areas where additional acetylene mixes with air, providing a reducing atmosphere, beneficial for preventing oxidation during welding.
   • Envelope: The outer envelope layer of the flame is composed of unburnt acetylene and partially burnt gases, which help in heat retention and provide a broader area of exposure for the material being welded.

3. Applications: This type of flame is commonly used for processes like brazing, soldering, and flame hardening, owing to its ability to provide increased heat and a controlled atmosphere.